zero: refactor telemetry and controller (#5135)

* zero: refactor controller

* refactor zero telemetry and controller

* wire with connect handler

* cr

internal/zero/telemetry/sessions/activeusers_test.go

@@ -0,0 +1,37 @@
+package sessions_test
+
+import (
+	"testing"
+	"time"
+
+	"github.com/stretchr/testify/assert"
+
+	"github.com/pomerium/pomerium/internal/zero/telemetry/sessions"
+)
+
+func TestActiveUsers(t *testing.T) {
+	t.Parallel()
+
+	startTime := time.Now().UTC()
+
+	// Create a new counter that resets on a daily interval
+	c := sessions.NewActiveUsersCounter(sessions.ResetDailyUTC, startTime)
+
+	count, wasReset := c.Update([]string{"user1", "user2"}, startTime.Add(time.Minute))
+	assert.False(t, wasReset)
+	assert.EqualValues(t, 2, count)
+
+	count, wasReset = c.Update([]string{"user1", "user2", "user3"}, startTime.Add(time.Minute*2))
+	assert.False(t, wasReset)
+	assert.EqualValues(t, 3, count)
+
+	// Update the counter with a new user after lapse
+	count, wasReset = c.Update([]string{"user1", "user2", "user3", "user4"}, startTime.Add(time.Hour*25))
+	assert.True(t, wasReset)
+	assert.EqualValues(t, 4, count)
+
+	// Update the counter with a new user after lapse
+	count, wasReset = c.Update([]string{"user4"}, startTime.Add(time.Hour*25*2))
+	assert.True(t, wasReset)
+	assert.EqualValues(t, 1, count)
+}